Variable condenser



11 1927' F. o. HARTMAN VARIABLE CONDENSER Filed Nov. 5. 1925 6sheets-Sheet INVENTOR, Z gfizrz zizayz ATTORNEY.

Jan. 11 1927.

F. o. HARTMAN VARIABLE CONDENSER Filed Nov. 5,

1935 6 Sheets-5heet F'. 0., HARYMAN VARIABLE CONDENSER Filed Nov.

5. 1925 6 Sheets-Sheet 4.-

Jan. 11, 1921. 14,42

F. o. HARTMA N VARIABLE CONDENSER I Filed 3 v. 5. i925 6 Sheets-Sheet 6t v m l '0- l l l l l i ih 3 w "vi amok ATTORNEY Patented Jan. 11,1927.

UNlTEDfSTATE'S PATENT oF ijca.

FRANK o. HARTMAN, or maasrmm, OHIO, lissreuoa TO THE HARTMAN memcn.manomc'ronmo comr'amr, or museum onto, A coaromrrron or 01:10.

VARIABLE commnsnn.

Application filed November 5, 1925. semi No. 67,152)

My invention relates broadly to electrical tuning systems and moreparticularly to a construction of timing apparatus for use in radiovbroadcast reception,

One of the objects of my invention is to provide a construction oftuning apparatus for radio reception by wh ch a number of electricalcircuits may be simultaneously circuits for the correction ofdifferences controlledbv a central adjustable unit.

Another object of my invention is to provide a construction of.variabletuning device for the s multaneous 'control of electricalcircuits, wherein provision is made for accurately balancing theseveral-electrical the capacity characteristics which may exist therein.

Another object of my invention is to providea construction of variablecondenser in which a multi-bladed rotor is provided working into a likenumber of stators with independently adjustable meuns associated witheach of the sets of stator 'plates' and arranged to be s aciallyregulated with. respect to indepen ent cooperating adjustable plates,connected to the several circuits under control-foraccurately comensating for difi'erences in the capacity 0 aracteristics thereof.

Stillanother object of my invention is to provide a construction ofvariable condenser in which a rotor .having a multiple number of rotorplatesthereon, may be accurately interleaved with a like number of independent sets of stator-plates for simultaneously'varying .the tuning ofa plurality of independent circuits.

My invention finds particular application in the s'niultaneous controlof a plurality of clectron'tube circuits of a radio frequency amplifierin a radio receiving apparatus for radio broadcast reception. Inapparatus of this kind it iscustomary to provrde anumber of tuningdialswhich control variable condensers which are. arranged to-tune theinput circuits of a plurality of electron tubes in succession. It isgenerally impractical to connect all of these condensers directly on thesame shaft for simultaneous operation by reason of the ditleycnr-es mthe characteristics of the various circuits. T provide 111021115: forsinmltaneously tuning the several electron tube c'rcnits, andindependent adjustable means tor-compensating for the differences in theseveral circuits. I have accomplished these results by a particularcon-.

s truction which will be described in detail in the s e'eificationhereinafter following. I desire t at it'be understood however that I donot intend my-invention to be limited to the particular constructionillustrated, but that my invention is entitled to the full scope ofmechanical equivalents.

I provide a rotor having a, plurality of rotor plates projecting froma.bentral shaft in a number of sets corresponding to the number ofcircuits which are to be controlled. The central' shaft of the rotorplates is journaled forrotation in such manner that the sets of rotorplates may be interleaved between correspondin sets of stator plateswhich project inwardfiy toward the central shaft, but are substantiallyinsulated therefrom. On the rear of each of the sets of stator plates Iprovide a plate extending substantially at right angles to the plane ofthe stator plates in such posiconstituting'the stator and rotor of thevariable condenserpermitsthe circuits to be so arranged that'accuratecompensation of the several circuits may be made corresponding todifferences in the electrical characteristics of the several tubes andcondensers and inductances in the circuits and then the circuitssimultaneously tuned by rotation of the central shaft. The details ofconstruction of the several parts of the condenser comprising myinvention will be more fully described hereinafter, by reference tothefollowing specification and the accompanying drawings, in which: v i

Figure 1 is a front elevation of a tunin apparatus which includes theprinciples 0 my invention; Fig. 2 is aback view of the tuning apparatusshowing the arrangement of the several sets of stator and rotor plates;Fig.3 is a side elevation showing the operating parts of the variablecondenser in the tuning system of my invention;-Fig. 4 is a detailedcross-sectional view taken on line 4--4 of Fig. 2 and'illustrating oneof the compensating capacity units employed in the tuning apparatus;Fig. 5 is a fragmentary cross-sectional view illustrating v theconstruction of the compensating capacity unit arranged to control fromthe front of the ill which is covered by a plate 2.

tuning panel of the tuning apparatus taken on line 5 of Fig". 2; Fig. 6is a central vertical section through the condenser showin the rotormounting; Fin. T is a vertical ion tal'enon line T-7 of Fig. 6; Fin. 8is adetail vertical sectional view taken on line 8 -3 of Fig. 6 showingthe construction of the gearing intermediate the rotor and the indicatordial of the apparatus; Fig. 9 is a rear plan view of a ,Inodiliedconstruction of tuning condenser; Fig. 10 is a side elevationof thecondenser construction illustrated in Fig. 9 Fig. 11. a central verticalsection taken through the rotor of the variable condenser constructionillustrated in 3; and Fig. 12 is a wiring diagram ing the arrangement ofthe tuning apparatus oi my inven ion in a radio receiving circuit. H

Referring to the drawings in detail, the apparatus panel is designatedby reference charact 1 having a sight opening i) therein The panel has acentrally positioned sight mark 4, with reference to which the calilations on a retary dial 5 may be read through the sight opening-.3 fromthe front of the apparatus. A control knob 6 projects through the frontoi the panel for controlling the movement of r the stub shaft 9 throughthe intermediary of a major. gear 12 with which a pinion 14 1s meshed...Control knobs 10 and 11 also project. throng-lithe. apparatus panel 1and are controlled from the trout thereof. The apparatus panel 1 is cutout or counter-sunk, as represented at to permit the dial 5 to be ireelyrotated therein. The variable condenser is mounted upon a panel ltiwhich is suitably secured to the rear of the apparatus panel 1. I haveillustrated a plurality of screws 17 which serve to position thesupporting plate 16 to the rear of the panel 1. A hub 18 is central ypositioned upon the plate 16 providing a central support for the stubshaft 9. The shaft 9 has an annular shoulder 19 which abuts against theface of the projecting hub 18 and is secured rigidly 'thereagainst. bymeans of a nut 20 which is screw threaded upon the end of the shaft 9bearinf' a qainst the front tare oi the panel 16. The stub shaft I? issubstantially larger indiameter throughout one portion of its lengthforming a bearing portion 21 with a 1 head?) at the end thereof. Therotor plates an end pl rotor plates may be secured with minimum frictionof parts. That is to say, the

space 2? may be filled with a lubricating grease well packed so that itis effective over a relatively long period of time. The method by whichthe rotor plates are varied in angular position will be more clearlyunderstood by reference to the details shown in Figs. (3 and S. A pairof U shaped plates and 23) are secured on opposite sides of plate 16forming a housing for a bearing 30. The bearing consists of asubstantially rectangular block havin a bore therethrough in which isjournaled the operating shat t. In Fig. 6 the control knob 6 is shownhaving its shaft 6 passing through the bore in the block 30. The block30 is substantially reduced at its opposite ends and fits snugly in anaperture in the U shaped plate 28, but in a position for verticaldisplacement in U shaped plate 29: by reason of the elongated aperture:11 in the'U shaped plate 29 and the relative pivotal mounting of theopposite end of the bearing block in the U shaped plate 28; The bearingblock 30 is spring-pressed by the resilient means indicated at 32 in adirection toward the major gear 12 whereby pinion 14 is constantly urgedinto engagement with the gear 12. The indicator 5 is geared to berotated with the angular dis-Y placement of the rotor plates 23 throughthe intermediary of pinion 33 o'f-shaft 34. The shaft. ill; is journaledin a bearing block '35 which is positioned between U shaped bracketmembers 536 and 37. The bearing block 35 is substantially rectangularand fits snugl into a correspondingly shaped aperture 38 in bracket '36.The ends of the bearing block are substantially reduced in width,enabling the block to be snugly titted between the bracket members 36and 537. The end f the bearing block 35 which projects into the bracket36 is provided with rounded edge faces 3.) enabling the bearing block torock in the bracket 36 in the mahner of a pivotal mounting. The bracket37 has a rectangular aperture 40 which is elongated in a verticaldirection. The bearing block 35 is normally spring pressed by means ofspring 41 which throws the bearing, block 35 to on side in the directionof the stub shaft 0. This tendency results in maintaining the major gear12 and pinion 533 in mesh and under uni'l'orm tension tl'lroughout allpositions ofangzular displrurment of the ro tor plate 23. l: may providea suitable stop member 42 mounted in fixed relation with respect. to theplate 10 and arranged to to operate with the projecting end 43 ot one ofthe bolt members 26 i'()-,])l.'t('ill(lt the X'Oik tion of the rotorplates ihrougrlrany gr ater ainric than 360 degrees in one direction. it

may be desirz le to have the rotor Upt'lziib in either direction throughmore than ih'il) degrees in which event I omit the stop construction. Itwill be observed that I have shaped the rotor plates to provide aplurality of sets of lates projecting outwardly from the stub s aft 9. Ido not wishto be limited to any particular number of these sets ofplates, as I have illustrated in Figs. 2, 3, 6 and 7, a triple set ofplates while in Figs. 9 and 10 I have shown two sets of plates. Thenumber of sets of plates is directl dependent upon the number ofindividual circuits which are to be adjusted. In Figs. 12, I have showna radio receivin apparatus including three stages of ra io frequencyamplification and accordingly I have illustrated three sets of plates.

Referring more particularly to Fig. 2 of the drawings. I haveillustrated three independent sets of statoialplates 44, and 46 whichpro'ert inwar y toward the stub shaft 9 an having their edges taperedsubstantially parallel with the edges of the rotor plates 23, when therotor is in 1mmmum capacity position with respect to'the stator plates.The stator plates 45, are shown built up On extended bolts 47 whichextend at substantially right angles to the insulated strips 48 and uponwhich are alternately positioned the stator plates 45 and spacingmembers 49. The sets of stator plates are each insulated from the suporting plate 16 in a manner as describe reference to the stator plates45, that is, the set of stator plates 44 is'insulatingly mounted withrespect to the supporting'plate ,16 by means of the. insulated strip 50,while the insulated strip 51 supports th stator plates 46. The insulatedstrips 48, 50 and 51 are suitably spaced from t 16' by members 52 whichform supporting feet beneath opposite ends of the strips. The statorplates 44 are built up on the vertically extending bolt members 53ancl54.

while the stator plates 46 are built up on the projecting bolt members55 and 56. In order to compensate for-'diflerences in the electricalcircuits with which the condenser is connectedindependent of the tuninobtained by the angular displacement o rotor plates 23 with respect tothe stator plates 44, 45, and 46, I provide fixed plates 57, 58 and 59which extend substantially at right angles to the sets of stator plates44,

45 and 46 along the rear thereof and; are

supported with respect thereto by tongue extensions which engage theends of the bolt members which support the stator plates. That is tosay, plate 57 is provided with extended tongues 57 and 57 which aresecured over the ends of the supporting bolt members 47 and 48. Plate 56is pro-.'

vided with extended tongues 58 and 58 in the upper corners of the plateand extending substantially at right angles to the surface of the platein such manner that the tongues may be secured upon the supportwith 1 iesupporting fplate,

mum capacity.

tended supporting bolts 53 and 54. It will" thercfore be seen that therear sides of each of the sets of stator, latcs 44, 45'a1id 46 aresubstantially closed y means of plates 57,

58 and 59. Cooperating plates 60, 61 and 62 are mounted adjacent each ofthe plates 57, 58 and 59 are supported from the base 16 by means oftongues which are bent at right angles to each of the plates. That is tosay, plate (30 is provided with tongues 60* and 60 which supporttheplate substantially at rightang les with respect to the base 16.Similarly, plate 61 is rovided with tongues 61 and 61 exten ing .atrightangles to the plate and securing the plate on the supporting base.16substantially at right angles to the rear edges of the Likewise, plate62 is provided with tongues 62 and 62 supported in spaced relation tothe plate 59 which closes the rear edges of stator plates 44. There issufficient from each of the lowerportions of lates 60, 61 and 62 to givethe plates su cient resiliency to enable the plates to be mechanicallyflexed or varied in special relation with stator plates enabling'theplate to be va0 y material cut away I respect to the plates 57, .58 and59. The mewhich an adjustable screw 64. is threaded 'chanical flexing ofthese plates may be seengaging one side of the plate 60in such mannerthat the plate 60 may be moved from its full line position in Fig. 4 toits dotted line position 60 which is a position of maxi- In this mannerdifferences in'the characteristics of the electrical circuits may becompensated. The adjustment of spacial relation of the plate 60 and. 57is; s own as being obtained wholly-within the with which the condensersare connected lio cabinet 65 which houses the tuning {appaf .ratus. Inorder toadjust the bapacity .val-

ues between the other sets (if plates-operating; means 10 and 11 arejactuated I provide cam members 11'- and 10 oh the shafts 1'1". and 10which extend through the bearings 11 and 10 supported from the \baseplate 16, and which operate to vary the spacial relation of the plates.By varying the anigular displacement of the operating means 10 and 11,the spacial relation between lates 61 and 68 and 62 and 59 may .besuitably varied to secure the desired compensation to enablesimultaneous control of all of the circuits. In '5 I have illustratedthe limits otthe compensating adjustments as sets of stator plates 67and 68.

In the modified construction of the tuning condenser illustrated inFigs. 9, 10, and 11, a sub-panel (56 of insulating material may besupported in spaced relation to the instrument panel 1 carrying theindependent The rotor plates are shown as comprising two sets and 70extending in diametrically opposite directions and supported in spacedrelation by spacing members 71 carried on shaft 72. The shaft 72 may beprovided with a conical bearinp member H which is secured by suitablemeans 75 to the sub-panel 66. The desired position of the extensions 69and T0 of the rotor plates may be secured by adjusting nut 76 on thethreaded portion 7? of the shaft T2 against the spring washer 76. Inthis manner the rotor plates may be set to a position exactlyintermediate the stator plates 67 and 68. The shaft 72 may be suitablycontrolled by knob 78 from the front of the panel 1. In the operation ofmy invention the variable condenser when employed as a uni-control forthe circuits of a radio receiving apparatus has the connections arrangedas illustrated in Fig. 12 where electron tubes 79 and 80 are arranged tofunction as radio frequency amplifiers while tube 81 operates as adetector and tubes 82 and 83 function as audio frequency amplifiers. Thereceiving apparatus is shown connected to an ZIHtQiLu. system 8% and=nn'd 85. The radio frequency ainplifier is shown constructed accordingto the principl in my 00- lending application t. 42,556, file July 9.H925,

and entitled Radio receiving system. The input and output circuits ofeach of the electron tubes are shown coupled through toroidaltransformers 86 and 87 while the antenna connection to the receiving setis coupled through a toroidal winding 88 all of which are described indetail in the above referred to co-pending application. The toroidalwinding 88 and the secondary windings S9 and of toroidal transformers S6and 87 are all tuned simultaneously. The rotor plates 23 of thecondenser are all connected to one end of each of the windings 8F, 89and 80. y The stator plates 44. 45 and 46 are each connected to theopposite ends of the windings 88, 89 and 90. The plates 57, 58 and 59'are illustrated as elect ically connected with each of the sets ofstator plates 4c 45 and 46 as hereinbeforc described, while plates 60,61 and 62 are variably related to the aforementioned plates and eachconnected to the ends of windings 88. 89 and 90 which are common in-therotor plates 23. It will be seenthat for different characteristics"ofthe electrolrtubcs T9, 80 and 81 that the capacity values between plates60-57, 5S-{il'and ill-62 may be so adjusted as to compensate fordifferences in the electrical characteristics of the tubes so thatsimultaneous and equal adjustment of the several tuning circuits may besecured by angular displacement of the rotor plates 23 with respect tothe stator plates.

The auxiliary or individual tuning condcnscrs do more than take care ofthe variation in the internal capacity between elements of therespective tubes. They make up for the variation in distributed capacityof the tuning condensers which coin rise the simultaneous controlfeature. Con ensers cannot. be practically made which are identical incapacity and with the positioning of the toroid coils there is also anunequal distribution of leads. The different length of leads togetherwith the dillerence in condenser capacity values add to the variation incapacity of the tube elements and it is this total "ariation that mycore denser construction compensates by means of the'individualcondensers.

While I have shown my invention as par ticularly adapted for the controlof multipie tuned radio frequency electron tube amplifier circuits itwill be understood that the variable condenser construction of minvention may be employed for the simu taneous adjustment of variouselectrical circuits and that I intend no limitation upon the applicationof my invention. While I .have described the variable condenserconstruction in certain Specific details, it will be understood thatmodifications may be made and that no limitations upon the invention'are intended other than are imposed by the scope of the appended claims.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is as follows I r 1. invariable electrical condenser comprisingin combination a central rotatable member, a plurality of rotor )latesprojecting radially from said rot-ate le member, a plurality ,of statorplates arranged adjacent said member and insulatingly supported withrespect thereto, said stator plates being disposed in the same planewith sui'l rotor platesg and auitiliary condensers connected across saidcooperating sets of stator and rotor plates and disposed substantiallyat right angles with respect to the plane of said plates, whereby themutual capacity between said cooperating sets of rotor and stator platesmay be simultaneously varied by angular movement of said rotor plateswith respect to said stator plates, and differences in electricalcapacity compensated for by independently actuating said auxiliarycondensers;

A variable electrical condenser comprising in combination a pluralityofsets of rotor plates arranged to interleave with a plurality of setsoi cooperating stator plates disposed substantially in the same planetherewith for simultaneously varying the "mutual capacity relationbetween'said cooperating sets, of stator and rotor plates and auxiharyvariable capacity means disposed substantiall at right angles withrespect tothe plane of said rotor and stator plates and electrlcallyconnected between each of said A cooperating sets of rotor and statorplates,

arranged to 'be independently actuated for compensating for differencesin th capacity relation between said cooperating sets of plates.

3. A variable condenser construction comprisin in combinationa rotatablemember, a set 0 rotor plates carried by said member, a cooperating setof statorplates with which said rotordp ates are arranged tobe'interleaved, sai rotatable member having a pair of inwardly extendingend plates forming bearing surfaces, and a journal comprising a stubmember extending outwardly from a panel forengaging; said bearingsurfaces whereby said rotatable member may be moved about said journalas a center for adjusting the mutual capacity relation between sa drotor and stator plates.

4. A variable condenser construction comprising in combination arotatable member, a set of rotor plates carried by said member, acooperating said rotor p ates are arranged to be interleaved, and ajournal for said rotatable member consisting of a stub member projectingoutwardly from a panel, said rotatable member having a pair of inwardlyextending bearing surfaces at opposite ends thereof arranged to engagesaid stub memberv and forming a housing for lubricant. therebetween,whereby said rotatable member may be readily revolved for interleavingsaid rotor plates with said stator plates in varyi g e a 3 5. A variablecondenser constructioncom- 7 rising in combination a panel, a stub memrprojecting outwardly from said panel, a

rotatab e member arranged to be journaled' on said stub member, aplurality of rotor. plates carried by said rotatable member and adaptedto be interleaved witha plurality of stator plates, said rotatablemember having a housin formed between a pair of end plates, said endplates projecting inwardly to form bearing surfaces for engaging saidstub member for enclosing within said rotatable member a lubricatingchamber where by said rotor plates may be angularly moved with respectto said stator plates with minimum friction.

6. A variable condenser construction comprising in combination with apanel, a stub member projecting from said panel, a rotatable memberjournaled upon said stub'member and carrying a plurality of tlpotorplates thereon, a plurality of statorfplates with which said rotorplates are arranged to interleave, a gear formed on one end of saidsetof stator plates with which rotatable member, an actuating shaftjournaled in said panel, a pinion on one end of said actuating shaftarranged to mesh with said gear, and means interposed between saidactuating shaft and said panel whereby said actuating shaft is free tomove within given limits in a plane passing through said stub member.

7. A variable condenser construction, the combination of a panel, a stubmember proecting from said panel, a rotatable member journaled upon saidstub member, a plurality of rotor plates carried by said rotatablememberand arranged to be interleaved with a plurality of cooperating statorplates, a gear carried by said rotatable member, and a rotary actuatorpaming through said panel and having a pinion ad- 'adjacent one endthereof meshing with said gear, said rotary actuator having meanswhereby said pinion is normally spring pressed intoengagement with saidear and arranged to be angularly moved wit respect thereto in the planeof said. stub'member for compensating for irregularities in movementrotatable member mounted adjacent said panel, a plurality of rotorplates carried by said rotatable member, a plurality of stator platesinsulatingly supported with respect to said rotor plates in such mannerthat said rotor-plates may be interleaved with said stator plates, aplate member substantially closing the rear of said stator plates and anauxiliary plate member mounted upon said supporting panel adjacent saidfirst mentioned plate, and means for varying the spacial relationbetween said plates members for independently compensating fordifferences in capadit variation-between said stator and rotor ates.

9. A variabl; condenser construction com prising in combination aplurality of sets of stator and rotor plates arranged in the same plane.and adapted to be interleaved with each other for varying the mutualcapacity, a substantially flat condenser plate secured to said statorplates and bending substantially at right angles to the plane of saidplates on one side of said plates away from that side at which saidrotor plates enter said stator plates and a resilientauxilaforementioned plate and adapted to be varied in spacial relationwith respect thereto.

10. A variable condenser construction comprising in'oombination arotatable meniber, a plurality of rotor lates carried by said rotatablemember, a p urality of stator plates into which said rotor plates arearran ed to. be interleaved, a gear carried by sa'i rotatable member. apanel, a stub memher projecting from said panel upon which saidrotatable member is 'ournaled, a rotary shaft actuator passing t roughsaid panel and car ing a pinion meshmg with said 5 gear, an a drivenshaft passing through said panel said driven sha'lh'carr ing a 1'0- taiindicator and a pinion mes g with sai gear, said shafts having means forconstantly urging said pinions into meshing with said gear, whileallowing said inions 1 to move in a plane passing through t e axis ofsaid rotatable member and compensatin for any irregularities in movementof sai gears.

FRANK O; HARTMAN.

